Estimating Apnea Phenotypes From Polysomnography: Oxygen
| Status: | Completed |
|---|---|
| Conditions: | Insomnia Sleep Studies, Pulmonary |
| Therapuetic Areas: | Psychiatry / Psychology, Pulmonary / Respiratory Diseases |
| Healthy: | No |
| Age Range: | 20 - 79 |
| Updated: | 4/17/2018 |
| Start Date: | November 2012 |
| End Date: | July 2016 |
Estimating Apnea Phenotypes From Routine Polysomnography: Application to Oxygen Therapy
This study seeks to employ advanced methods to estimate the individual factors contributing
to sleep apnea from standard recordings made during routine clinical sleep studies. This
study focuses on breathing control or "loop gain" as one of the factors contributing to sleep
apnea. Increased levels of oxygen in the air is known to make breathing more stable by
lowering "loop gain". Here, our goal is to use a new method capable of detecting a reduction
in loop gain with oxygen. The investigators also aim to test whether a high loop gain
measured at baseline/placebo predicts a greater improvement in sleep apnea with oxygen
therapy.
to sleep apnea from standard recordings made during routine clinical sleep studies. This
study focuses on breathing control or "loop gain" as one of the factors contributing to sleep
apnea. Increased levels of oxygen in the air is known to make breathing more stable by
lowering "loop gain". Here, our goal is to use a new method capable of detecting a reduction
in loop gain with oxygen. The investigators also aim to test whether a high loop gain
measured at baseline/placebo predicts a greater improvement in sleep apnea with oxygen
therapy.
In a single-blinded randomized crossover study, inspired oxygen/air (40%/21%) is delivered on
two separate nights. Loop gain is measured from routine polysomnography using a novel
mathematical method. A value of loop gain >1 reflects unstable breathing, and a value less
than but approaching 1 denotes a system more prone to oscillate. Loop gain is measured as the
changes in ventilatory drive/effort that arises subsequent to changes in ventilation (e.g.
due to obstructive apnea). A simple chemoreflex model (gain, time constant, delay) is fit to
surrogate ventilation data (derived from airflow) during sleep. The best model is one that
best matches the elevated ventilatory drive (measured as ventilation in the absence of
airflow obstruction) based on the prior apneic/hypopneic fall in ventilation. Loop gain is
calculated from this model. We aim to use loop gain measured on and off oxygen to determine
whether a strong response (reduction in apnea severity) can be predicted by a higher loop
gain (in the sham arm) using our method. We also assessed whether assessing upper airway
anatomy/collapsibility, dilator muscle responsiveness, and the arousal threshold helped to
predict responses to treatment.
two separate nights. Loop gain is measured from routine polysomnography using a novel
mathematical method. A value of loop gain >1 reflects unstable breathing, and a value less
than but approaching 1 denotes a system more prone to oscillate. Loop gain is measured as the
changes in ventilatory drive/effort that arises subsequent to changes in ventilation (e.g.
due to obstructive apnea). A simple chemoreflex model (gain, time constant, delay) is fit to
surrogate ventilation data (derived from airflow) during sleep. The best model is one that
best matches the elevated ventilatory drive (measured as ventilation in the absence of
airflow obstruction) based on the prior apneic/hypopneic fall in ventilation. Loop gain is
calculated from this model. We aim to use loop gain measured on and off oxygen to determine
whether a strong response (reduction in apnea severity) can be predicted by a higher loop
gain (in the sham arm) using our method. We also assessed whether assessing upper airway
anatomy/collapsibility, dilator muscle responsiveness, and the arousal threshold helped to
predict responses to treatment.
Inclusion Criteria:
- Apnea/hypopnea index >20 events per hour
- Age 20-79 years
Exclusion Criteria:
- COPD with desaturation (resting SpO2<96%)
- Use of respiratory stimulants or depressants
- Pregnancy
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